Tellurium extraction from copper electrorefining slimes

Abstract

The present invention is concerned with a method for the substantially selective extraction of tellurium from copper electrorefining slimes. The method comprises maintaining a molar ratio Ag/Se, Ag/S or Ag/Se+S at a value of about 2 or less in the slimes during leaching thereof in an autoclave. The excess of selenium and/or sulphur allows the formation of Ag 2 Se or Ag 2 S, which remains insoluble during autoclave leaching.

What is claimed is: 
     
       1. A method for extracting tellurium from a material containing tellurium and silver, the method comprising the steps of: mixing the tellurium and silver-containing material with an acidic solution to obtain a slurry;   after said mixing, adding to said slurry selenium, a selenium-containing compound, elemental sulphur, or mixtures thereof in an amount such that the molar ratio silver/selenium, silver/sulphur or silver/selenium+sulphur is 2 or lower;   leaching the slurry in a vessel under oxygen partial pressure to selectively solubilize the tellurium while retaining the silver in a solid phase of the slurry; and   carrying out a solid/liquid separation to recover the dissolved tellurium.   
     
     
       2. A method according to claim 1 wherein the tellurium-containing material comprises copper electrorefining slimes. 
     
     
       3. A method according to claim wherein the selenium is in the form of elemental selenium, H 2  SeO 3  or Na 2  SeO 3 . 
     
     
       4. A method according to claim 1 wherein the vessel comprises an autoclave. 
     
     
       5. A method according to claim 1 wherein the acidic solution comprises a sulphuric acid solution. 
     
     
       6. A method for extracting tellurium from copper electrorefining slimes containing tellurium and silver, the method comprising the steps of: mixing the slimes with diluted sulfuric acid to obtain a slurry;   after said mixing, adding to said slurry selenium, a selenium-containing compound, elemental sulphur, or mixtures thereof in an amount such that the molar ratio silver/selenium, silver/sulphur or silver/selenium+sulphur is 2 or lower;   leaching the slurry in an autoclave under oxygen partial pressure to solubilize the tellurium without solubilizing the silver; and   carrying out a solid/liquid separation to recover the dissolved tellurium.